<!doctype html>
<meta charset="utf-8">
<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1861027">
<script src=/resources/testharness.js></script>
<script src=/resources/testharnessreport.js></script>
<script src=/resources/testdriver.js></script>
<script src=/resources/testdriver-actions.js></script>
<script src=/resources/testdriver-vendor.js></script>
<fieldset id="fieldset" disabled>
  <input id="target">
</fieldset>
<script>
const target = document.getElementById("target");
const fieldset = document.getElementById("fieldset");
promise_test(async function() {
  await new Promise(r => window.addEventListener("load", r, { once: true }));
  assert_true(target.matches(":disabled"), "Fieldset disables the input");
  assert_true(target.matches(":read-only"), "Disabled implies read-only");

  // Try to focus, it shouldn't be focusable.
  target.focus();

  assert_not_equals(document.activeElement, target, "Should not be focusable");

  fieldset.removeAttribute("disabled");

  assert_false(target.matches(":disabled"), "Should go back to writable");
  assert_false(target.matches(":read-only"), "No longer read-only");

  // Should be focusable now.
  target.focus();

  assert_equals(document.activeElement, target, "Should not be focusable");

  await test_driver.send_keys(target, "A");
  assert_equals(target.value, "A", "Typing should work");
});
</script>
